The most probable reason that the alkaline earth metals give dipositive ions instead of unipositive ion is

Options

A. The compounds with `+2` oxidation state have more lattice enthalpy than those with `+1` oxidation state.
B. The values of their first and second ionisation potential are not very much different.
C. The dipositive ion has grater charge than the unipositive ion.
D. The compounds of `+1` oxidation state of these metals are not stable.

Answer

To understand why alkaline earth metals predominantly form dipositive ions (like Mg²⁺ and Ca²⁺) instead of unipositive ions (like Mg⁺), we can analyze the electronic configuration and stability associated with these ions.

### Step-by-Step Solution:

1. **Identify the Electronic Configuration**:
- Alkaline earth metals (Group 2) have the general electronic configuration of \[ ns^2 \], where \( n \) is the principal quantum number. For example, magnesium (Mg) has the configuration \[ 1s^2 2s^2 2p^6 3s^2 \].

2. **Understanding Ionization**:
- To form ions, these metals can lose electrons. The first ionization involves removing one electron, resulting in a unipositive ion (e.g., Mg⁺). The second ionization involves removing the second electron, leading to a dipositive ion (e.g., Mg²⁺).

3. **Stability of Ions**:
- When an alkaline earth metal loses both of its valence electrons, it achieves a stable noble gas configuration (e.g., Mg²⁺ achieves the configuration of neon). This configuration is energetically favorable.

4. **Energy Considerations**:
- The energy required to remove the first electron (first ionization energy) is less than that required to remove the second electron (second ionization energy). However, the total energy required to remove both electrons is less than the energy required to stop at the unipositive state.

5. **Lattice Enthalpy**:
- Compounds formed by dipositive ions generally have higher lattice enthalpy compared to those formed by unipositive ions. This means that the formation of dipositive ions is favored energetically due to stronger ionic bonds in the resulting compounds.

6. **Conclusion**:
- Therefore, the most probable reason that alkaline earth metals give dipositive ions instead of unipositive ions is that the compounds with a +2 oxidation state have more lattice enthalpy than those with a +1 oxidation state, making the formation of dipositive ions more favorable.